Rainshafts galore

How great was yesterday with the “return of the shafts”!  Though we only received a trace here in Catalina, you knew, if you saw them, that some small areas were getting drenched.

How much?

The Pima County Alert Network indicates that 0.28 inches was the most that fell in their gages.  But, from experience, you can bet that somewhere up to half an inch fell on somebody out there, judging by shaft density and the height of the cloud bases–bases were a bit on the high side, at around 10,000 feet above the ground (and moderately cool at 5-6 C) .  Will post a radar-derived 24 h rain total map when it comes out (it has) from Intellicast.com. (Gee, there it is and that eye-ball assessment seemed pretty accurate.)

Below are some shots of those glorious, local, late breaking, rainshafts. (Was about to give up on rain in mid-afternoon since Cumulus development had stagnated.  But as happens, the atmosphere changes, maybe got hot enough with our 103 F at about the time these boys took off, and, voila, up the tops of those Cu went pretty much all around us.

Note the baby rainshaft below.  They’re pretty special.  If you were to get in one, you would see that it was pouring rain, but only on you.  You could look and couple of hundred yards in every direction and see that it was only raining on YOU. You’d feel pretty special about yourself; maybe boost that self-esteem a bit.

If you want the full review of yesterday’s excitement, go here to the U of A time lapse movie.  You’ll see the sky change drastically after about 4:30 PM (if you can read the tiny time hack in the lower right hand corner.)

Today?

The amount of water over us continues to climb, and surface dewpoints reflect that, some in the 60s (61 F here in Catalina now)–meaning a lot of water vapor is around, the fuel of a good rainstorm.  The local model run from the U of AZ based on 06Z (11 PM LST) data doesn’t have a lot going on hereabouts, it seems to expect today to be a lot like yesterday–but that would be good.

However, with cloud bases likely to be lower and warmer, that will mean bigger dumps in those rainshafts as more water funnels up into those rising afternoon Cumulonimbus turrets.  Hoping for a special e-mail later this morning from the U of A summer rain specialists, always exciting since they only issue them when they think something “good” is going to happen.  Didn’t get one yesterday, deemed to tame a day maybe.  BTW, “good” is defined by meteorologists as heavy rain, blowing dust from outflow winds, flash floods, lightning, maybe some hail thrown in, etc.

4:45 PM.
4:51 PM
5:19 PM. Baby rainshaft, so cute! Wish I could have gone over there and stood under it.
5:46 PM. Shower line moves southwestward across Marana.
7:28 PM. Still going, but in the distance. Nice lightning show out that way until well after midnight.

By Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.